Although employers complain about the rising cost of providing retiree health benefits, many companies in fact face limited financial exposure to health-care inflation -- no matter how sick their retirees get or how long they live.

That's because at least half of the nation's major employers, including International Business Machines Corp., CSX Corp. and Aon Corp., have established ceilings on the amount they will spend each year on an individual retiree, according to a survey of 435 large companies by the Kaiser Family...